Cruise control surging
- Thread starter Rondo
- Start date
Jesus Freak
Full Access Member
My guess is a slightly clogged fuel filter that just can't hack it at that pressure or demand. I doubt its the actual cruise control stuff.
I was thinking about lack of fuel. I have a holly red pump. If I lightly place my foot on the throttle it will hold it steady but I can feel it fluctuate the pedal. If I don’t use cruise I can hold the throttle anyplace, even 85 mph and it will run steady. I think that eliminates any fuel issues. I’m wondering if something is allowing the motor to move around in the cruise box.
Jesus Freak
Full Access Member
Yeah, you got a quirk.
I recently got a 1993 F-250 stock under the hood 7.3 idi. The speedometer would flutter/surge and also the tach, mainly when got up near 40 mph and upwards from there. I changed the FSS switch on the punkin, twice. No change. Also replaced the overdrive switch (E4OD), but the speedometer/tach still fluttered/surged. The local mechanic shop 'eventually' found that if disconnected the ABS connection/switch (behind the glove box in the dash) that it eliminated the fluttering/surging. I opted to leave the ABS disconnected - ABS wasn't that good on that older truck anyway. Now the brakes are like on my '86 F-250 and no speedometer/tach fluttering/surging. Does this make sense? I don't know, but the truck speedometer and tach operates like it should now. May or may not have any relationship to your problem/situation???? This truck has 114k original miles. Due to previous owner loading/unloading boats at a lake, had to go through the entire rear end/axle/bearing/brakes and had a Eaton Detroit TruTrac locker installed. The E4OD tranny seems to be functioning/operating like it should. Before the above things were done, the truck would surge/pulsate when in cruise control, around 40 mph and higher, as did the speedometer and tach. I miss having my manual transmission, as in my other 2 trucks...
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Glad it worked for your situation.
With the abs module disconnected, I still get a very slight engine pulse (speedometer does ok) at 70 mph using cruise control. I find that if I gently apply a bit of pressure on the throttle pedal, it stops pulsing. Though it seems to also tend to fade away from pulsing if let it run on cruise control only (no foot pressure), after a few miles - or perhaps I'm just use to it then?? oh well... Sure do like this new-to-me '93 idi.
With the abs module disconnected, I still get a very slight engine pulse (speedometer does ok) at 70 mph using cruise control. I find that if I gently apply a bit of pressure on the throttle pedal, it stops pulsing. Though it seems to also tend to fade away from pulsing if let it run on cruise control only (no foot pressure), after a few miles - or perhaps I'm just use to it then?? oh well... Sure do like this new-to-me '93 idi.
Attachments
Been awhile commenting on this situation: speedometer pulsing/stuttering/bouncing.
From the above Posts, the tach is working properly, not bouncing, in my '93 73.idi.
The speedometer still pulsing/stuttering/bouncing, I'll explain here:
1. speedometer needle holds where it should until over 45 mph, then it will pulse/boince some. It increases the activity the higher mph's I go. Example: at 70 mph, it will hold for a second or three, then it bounces back down to 60 mph. Keeps on doing this.
2. have seen comments this might be due to air infiltration/leak in the fule line(s), somewhere?
3. a few days ago, on my way back from Wyoming to Montana, had checked the tranny fluid and when closed the hood, it didn't close/latch all the way down/closed. As I was back out on the Interstate and up to around 70+ mph, noticed the speedometer needle was bouncing/jumping from 70 mph clear down to 30 mph, all places inbetween and the back-n-forth - very quickly up n' down the needle went. I noticed the hood wasn't closed all the way/tightly. I immediately pulled to the side of the road and closed the hood tightly.
4. when back out on the Interstate and up to 70 mph again, the speedometer needle did its usual 70 mph down to 60 mph and bauncing bacnk-n-forth again.
5. when the truck gets up over 40-45 mph, there is x amount of air flow through the engine compartment/underneath the truck. When get up to 70 mph the air flow is increased much higher. When the hood was not closed all the way, that greatly increased the air flow through the engine compartment, causing the speedometer needle to REALLY go spastic.
6. the various levels of air flow contributes to the air infiltration/flow across fuel lines. Meaning(?), with an open/infiltration condition in a fuel line, the various increases in speedometer needl bouncing is caused?
What think you out there?
thanks and hope this helps others...
From the above Posts, the tach is working properly, not bouncing, in my '93 73.idi.
The speedometer still pulsing/stuttering/bouncing, I'll explain here:
1. speedometer needle holds where it should until over 45 mph, then it will pulse/boince some. It increases the activity the higher mph's I go. Example: at 70 mph, it will hold for a second or three, then it bounces back down to 60 mph. Keeps on doing this.
2. have seen comments this might be due to air infiltration/leak in the fule line(s), somewhere?
3. a few days ago, on my way back from Wyoming to Montana, had checked the tranny fluid and when closed the hood, it didn't close/latch all the way down/closed. As I was back out on the Interstate and up to around 70+ mph, noticed the speedometer needle was bouncing/jumping from 70 mph clear down to 30 mph, all places inbetween and the back-n-forth - very quickly up n' down the needle went. I noticed the hood wasn't closed all the way/tightly. I immediately pulled to the side of the road and closed the hood tightly.
4. when back out on the Interstate and up to 70 mph again, the speedometer needle did its usual 70 mph down to 60 mph and bauncing bacnk-n-forth again.
5. when the truck gets up over 40-45 mph, there is x amount of air flow through the engine compartment/underneath the truck. When get up to 70 mph the air flow is increased much higher. When the hood was not closed all the way, that greatly increased the air flow through the engine compartment, causing the speedometer needle to REALLY go spastic.
6. the various levels of air flow contributes to the air infiltration/flow across fuel lines. Meaning(?), with an open/infiltration condition in a fuel line, the various increases in speedometer needl bouncing is caused?
What think you out there?
thanks and hope this helps others...
Rdnck84_03
Full Access Member
I highly doubt that airflow under the hood has any bearing on the bouncing speedometer. Not going to say it is impossible, I just think it is highly unlikely.
I'm not sure what all you have done to try and correct the issue but I would start with the speed sensor and pigtail at the sensor.
James
I'm not sure what all you have done to try and correct the issue but I would start with the speed sensor and pigtail at the sensor.
James
Yes, probably a bit of a stretch (air flow) but it did alter the speedometer needle bouncing.
It's puzzling!
If by speed sensor, do you mean the VSS? Have replaced the VSS and checked out the connector/wiring/pigtail(VSS wiring connector?).
There have been comments about air infiltration with/regarding fuel lines/system.
It's puzzling!
If by speed sensor, do you mean the VSS? Have replaced the VSS and checked out the connector/wiring/pigtail(VSS wiring connector?).
There have been comments about air infiltration with/regarding fuel lines/system.
Rdnck84_03
Full Access Member
Air intrusion has nothing to do with airflow around the engine. It is usuall air drawn in by the fuel pump by a compromise connection before the fuel pump.
For the sake of the air intrusion line of thought, does the tachometer jump around corresponding to the speedometer? If not and the engine runs good, I would stop worrying about air intrusion and concentrate on the speedometer and related components.
James
For the sake of the air intrusion line of thought, does the tachometer jump around corresponding to the speedometer? If not and the engine runs good, I would stop worrying about air intrusion and concentrate on the speedometer and related components.
James
When first got the truck, tach and speedometer both jumped around.
Disconnected the ABS, behind the glove box, and the tach quit jumping.
But the speedometer still jumps.
Engine runs good.
Will scout out "a compromise connection before the fuel pump."
I do some mechanicing, but I'm a 'shade-tree' mechanic of sorts, so some of this is foreign to me.
To my basic logical thought: speedometer jumps a certain way; then the increase in air with the hood slightly open and the speedometer was going bonkers, closed the hood and the speedometer went back to the same 'some jumping'. Just seemed strange to me.
Appreciate your input, thank you.
This seems to hold potential with the situation:
www.oilburners.net
Disconnected the ABS, behind the glove box, and the tach quit jumping.
But the speedometer still jumps.
Engine runs good.
Will scout out "a compromise connection before the fuel pump."
I do some mechanicing, but I'm a 'shade-tree' mechanic of sorts, so some of this is foreign to me.
To my basic logical thought: speedometer jumps a certain way; then the increase in air with the hood slightly open and the speedometer was going bonkers, closed the hood and the speedometer went back to the same 'some jumping'. Just seemed strange to me.
Appreciate your input, thank you.
This seems to hold potential with the situation:
Random surging while driving
Mornin' folks. Just had an issue come up with 94: While driving the truck will surge a little bit, acting like I suddenly hammered the throttle down. Usually lasts a handful of seconds and then goes back to it's normal sluggish self. Seems to happen once the truck is warmed up a bit, as in, it...
www.oilburners.net
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Rdnck84_03
Full Access Member
Just my thoughts, I am going to guess that stopping to close the hood had more to do with the stopping than closing the hood.
When I first bought my '99 powerstroke back in '10 the speedometer would work fine. Stop for whatever reason and take off again, speedometer won't move at all. Next stop it may or may not work, it was a crap shoot.
For whatever reason if it was working it would stay that way until the signal came to a complete stop. Sometimes it would work after a stop sometimes it wouldn't, if it didn't it would stay non operational until after it came to a complete stop again.
After replacing the speed sensor and pigtail it fixed it, still functional now.
James
When I first bought my '99 powerstroke back in '10 the speedometer would work fine. Stop for whatever reason and take off again, speedometer won't move at all. Next stop it may or may not work, it was a crap shoot.
For whatever reason if it was working it would stay that way until the signal came to a complete stop. Sometimes it would work after a stop sometimes it wouldn't, if it didn't it would stay non operational until after it came to a complete stop again.
After replacing the speed sensor and pigtail it fixed it, still functional now.
James
